I suffered from a Power_driver_state_failure problem, which Windows7 forums helped fix. However at some point the problem appears to have damaged my windows Installer. I am having problems installing new updates on my Norton and itunes no longer works and will not reinstall. The message I keep getting is - 'The windows installer service could not be accessed. This can occur if you are running windows in safe mode, or if the windows installer is not correctly installed. Contact your support personnel for assistance.
I have tried to reinstall my Windows 7 disk, but this has had no effect.